The isolation of stem cells is a critical technology for the treatment of a wide range of diseases. Since stem cells can proliferate and differentiate, their isolation facilitates transplantation and gene therapies as well as understanding the basic process of hematopoiesis. While progress has been made in the isolation of stem cells through biotin-avidin based immunoadsorption and fluorescence-activated cell sorting, improvements are still needed in order to increase yields, purity and rapidity of processing of stem cells. Recent advances by AmberGen, Inc. in the field of photocleavable reagents provide the basis of the proposed research. Photocleavable biotins allow specific cells to be separated from a heterogeneous population through the biotin-avidin interaction and then released by light. Photocleavable markers can be attached to cells through antibodies for cell sorting and then removed by light. Recent progress shows these photoreagents can be designed to photocleave at red-shifted wavelengths which are non-damaging to cells. Research will also be directed at the design and production of a novel class of antibodies whose interaction with antigens can be modulated by light. AmberGen, Inc. will synthesize and evaluate a variety of photocleavable biotins, photocleavable markers and light-activated amino acids for the isolation of stem cells. PROPOSED COMMERCIAL APPLICATION: Development of new technology based on photocleavable biotins (PC-Biotin TM), photocleavable markers (PC-Marker TM) and Light modulated antibodies (LM-Antibodies TM) will have commercial applications for the isolation and detection of a wide variety of cells including stem cells and pathogens. Potential products include PC-Biotin TM and PC-Marker TM compounds, antibody-PC-Biotin TM/antibody-PC-Marker TM conjugates, photocleavable FACS labels, kits for cell isolation and automated devices for cell separation.